1. Field of the Invention
This invention relates to catheters placed in the veins or arteries of animals and humans for the continuous transmission of fluids. Often catheters become unusable due to blockage of the vein or artery distal to the tip of the inserted catheter. The present invention consists of a specialized cannula and associated intraluminal cannula placement apparatus for inserting the specialized cannula into and through the lumen (hollow center cavity) of a previously inserted standard I.V. catheter so that the tip of the specialized cannula extends substantially beyond the tip of the catheter to beyond a point of blockage.
2. Description of the Prior Art
In medical and veterinary practice it is common procedure to provide fluids and medications to patients through a catheter. The typical catheter used today has a female Luer fitting (standard I.V. catheter hub) on the proximal end to which fluid lines or medication introducing devices can be attached. The catheter is typically inserted into a vein in the hand, forearm, or forelimb in humans and in domestic cats, dogs, or other companion and domesticated animals. Often fluids are administered through the cephalic vein, a large superficial vein in the forelimb running from the hand or paw to the shoulder. The injection site is generally on the anterior surface of the limb, between the carpals and the elbow joint. However, depending on the circumstances, the catheter may be introduced in other areas. Puncturing of the skin for placement of the catheter is accomplished by a sharpened needle located inside the catheter that protrudes beyond the tip of the catheter. Even in skilled hands, the insertion of the catheter is not without some discomfort to the patient and can be traumatic especially in young and old human patients and in animals of any age. Since catheters are usually placed away from the first major limb joint, constriction of the vein or artery and obstructions to blood flow on the heart side of the catheter insertion point can occur if the joint is flexed and kept in a flexed position for any length of time. Continued flexion is more common in young and old human patients and in sedated animals that do not move around. Constriction may also occur due to other circumstances. When this occurs, prescribed fluid or medicant administration is interrupted. If occlusion of a vein persists, the catheter may become clotted and prevent further treatment.
When constriction seriously impedes the flow of fluid through the catheter, typical remedies are either to apply an external splint to restrict movement of the offending joint, to withdraw the catheter and replace it with another longer catheter more resistant to constriction/obstruction, or to withdraw the catheter and insert a new catheter above the point of constriction. The accompanying pain/discomfort of the replacement procedure, especially if locating the vein or artery proves difficult, makes an alternative procedure desirable. The specialized cannula and intraluminal cannula placement apparatus of the present invention alleviates the need for placement of a new catheter by providing a mechanism for the fluid tight insertion into and through the previously inserted catheter of a specialized cannula that is sufficiently long to bypass the point of constriction. The specialized cannula has an outside diameter that is smaller than the inside diameter of the standard I.V. catheter which allows the specialized cannula to be slidingly inserted through the catheter. For this reason, the specialized cannula is referred to as an intraluminal cannula. Despite the reduced diameter of the specialized cannula, sufficient flow of fluids for medical treatment can be maintained. As will be described in greater detail below, after insertion of the specialized cannula, the cannula placement assembly is detached and standard fluid lines or medication delivering devices can be fastened to the standard I.V. catheter hub as before. None of the prior art patents teaches the solution provided by the present invention.
In U.S. Pat. No. 7,156,836, Teo teaches a double cannula assembly that is used to overcome the problem of clotting within a cannula. In this invention, an outer cannula previously placed in a vein has inserted into it a smaller diameter inner cannula. The contacting surfaces between the outer surface of the inner cannula and the inner surface of the outer cannula provide a sliding tight fit which is sufficient to allow insertion of the inner cannula but tight enough to prevent blood or other fluids from seeping between the two surfaces. Since clots frequently form at the tip of the cannula, removing and inserting an inner cannula displaces the clot and reopens the passageway. When clotting occurs, the inner cannula is removed, leaving the outer cannula in place. If desired, a new inner cannula may then be inserted through the outer cannula.
In U.S. Pat. No. 3,633,579, Alley, teaches a device for placing an inner catheter within a cannula that has been previously inserted with a needle. A tapered locking ferrule coaxial with and surrounding the catheter is used to secure the catheter to the previously placed cannula. The ferrule is slid along the catheter until the distal end of the tapered ferrule enters a tapered proximal opening in the rear of the cannula. The ferrule is made of a softer material than that of the previously placed cannula, so that the ferrule may be wedged into the cannula taper, said wedging action causing the ferrule to constrict and grip the outer surface of the catheter thereby locking the catheter against axial movement relative to the cannula. The previously placed cannula does not have a standard I.V. catheter Luer lock at the rear end, and therefore, the previously placed cannula is incapable of attaching to the Luer lock of another cannula placement device.
In U.S. Pat. No. 3,515,137, Santomieri teaches a catheter unit using one cannula, which is placed using a leading needle and an inserter. The inserter is coaxial with the cannula, surrounds the cannula, and is made of a resiliently compressible material. Compressing the inserter grips the cannula and needle for insertion. After puncture and insertion, the grip on the inserter is loosened so that the needle may be withdrawn. The inserter can then be used to grip just the cannula to advance the cannula further into the vein. Repeatedly using the inserter to grip the cannula to advance it forward, and then loosening the cannula and sliding it towards the end of the cannula enables the user to advance the cannula as far as is desired into correct position within the body.
U.S. Pat. No. 4,235,232 by Spaven et al. teaches a hub device for use with catheter placement where the catheter is inserted through a dimple in the elastomeric material of the hub, which forms a seal around the catheter.
U.S. Pat. No. 4,613,329 by Bodicky teaches a catheter placement device with an elastomeric grommet with bore, through which the catheter is placed, said grommet permitting relatively low resistance to distal movement of the catheter and relatively high resistance to proximal movement of the catheter.
U.S. Pat. No. 4,068,659 by Moorehead and U.S. Pat. No. 4,068,660 by Beck teach a sterilizable disposable assembly for inserting a catheter into a vein wherein the catheter is located inside the needle and connected sheath during insertion. After insertion, pressure is applied to the skin above the insertion site to capture/hold the catheter in the vein while the needle is withdrawn. The trailing end of the catheter is pushed out of the sheath by the advancement of the leading edge of an inserter, which can be advanced by a handle protruding out of the sheath. The inserter has attached a stiffener, smaller in diameter and coaxial with the catheter, that extends substantially the length of the catheter. The stiffener is attached at the leading edge of the inserter and keeps the catheter from unduly flexing during insertion but is otherwise not attached to the catheter. The catheter placement assembly is discarded following placement of the catheter.
U.S. Pat. No. 4,205,675 by Vaillancourt teaches a catheter placement unit that is used with an introducer needle and introducer catheter. The catheter placement unit contains a connector with an internal bore and a male fitting for coupling to the catheter fitting to create a connection.
U.S. Pat. No. 4,634,433 by Osborne teaches a flexible sheath assembly for protecting the sterility of the exposed portion of a catheter, where the unexposed portion has been placed in a vein. When it is necessary to adjust the depth of insertion of the catheter, the flexible sheath assembly encasing the exposed portion of the catheter preserves the sterility of the catheter so that the depth of insertion can be adjusted without causing contamination. U.S. Pat. No. 4,767,409 by Brooks and U.S. Pat. No. 4,834,710 by Fleck similarly teach devices for protecting a catheter from contamination during and after placement in a vein.
U.S. Pat. No. 6,156,016 by Maginot teaches a catheter system comprising a guide catheter with guide lumen extending between a distal guide orifice and a proximal guide orifice. The catheter system also includes an original catheter within the guide lumen of the guide catheter. In addition, the system features a replacement catheter within the guide lumen of the guide catheter.
U.S. Patent Application Publication 2006/0116629 A1 by Tal et al. teaches a catheter insertion apparatus with a catheter featuring a first and second lumen. A first member moves within the first lumen to create a cavity, and a second member moves within the second lumen. Furthermore, the cavity created by the first member is designed for movement of the second member.
U.S. Patent Application Publication 2007/0100295 by Belley et al. teaches a device for use with catheter apparatus that features an internal seal.